Mixtures of optical brighteners

ABSTRACT

A mixture of optical brightener compounds consisting of a compound of formula (A)    &lt;IMAGE&gt;  (A)  and at least one compound of formula (B) or (C) where formula (B) is    &lt;IMAGE&gt; (B)   and formula (C) is &lt;IMAGE&gt; (C)

This is a division of application Ser. No. 214,227, filed Dec. 8, 1980,now U.S. Pat. No. 4,380,514.

The present invention relates to a process for the preparation ofunsymmetrically substituted compounds of the general formula I ##STR4##where X and Y independently of one another are hydrogen, fluorine,chlorine, cyano, C₁ -C₁₀ -alkoxycarbonyl, unsubstituted or substitutedcarbamyl or sulfamyl, a sulfonic acid aryl ester group, C₁ -C₁₀-alkylsulfonyl or phenylsulfonyl, and at least one of X and Y is nothydrogen, and of mixtures of such optical brighteners, whereinterephthalaldehyde is reacted successively with a compound of thegeneral formula IIa ##STR5## and a compound of the general formula IIb##STR6## where X and Y have the meanings and alkyl is preferably C₁ -C₄-alkyl, in the presence of an alkali, in a solvent from which themonocondensation product precipitates.

COOCH₃, COOC₂ H₅, COOC₃ H₇, COOC₄ H₉, COOC₆ H₁₃, COOC₈ H₁₇, ##STR7##COOC₁₀ H₂₁, COOC₅ H₁₁, CONHCH₃, CONHC₂ H₅, CONHC₃ H₇, CONHC₄ H₉, CONHC₆H₁₃, CONHC₈ H₁₇, CON(CH₃)₂, CON(C₂ H₅)₂, CON(C₃ H₇)₂, CON(C₄ H₉)₂,##STR8## CONHC₂ H₄ OH, CON(C₂ H₄ OH)₂, CONHC₂ H₄ OCH₃, CON(C₂ H₄ OCH₃)₂,CON(C₂ H₄ OC₄ H₉)₂, ##STR9## the corresponding sulfamyl radicals, SO₂OC₆ H₅, SO₂ OC₆ H₄ CH₃, CH₃ SO₂, SO₂ C₂ H₅, SO₂ C₄ H₉, SO₂ C₆ H₁₃ andSO₂ C₈ H₁₇.

Suitable solvents for the reaction include, in particular, esters,ethers, hydrocarbons and chlorohydrocarbons, eg. ethyl acetate, n- andi-butyl acetate, methyl-glycol acetate, n- and i-propyl acetate,1,2-dimethoxyethylene, diethylene glycol dimethyl ether,tetrahydrofuran, dioxane, toluene, xylene and chlorobenzene.

Preferred solvents are ethyl acetate, n- and i-butyl acetate,methylglycol acetate, tetrahydrofuran and dioxane.

The process according to the invention is advantageously carried out bydissolving the terephthalaldehyde in the solvent and then adding thecompound of the formula IIa, followed by slow addition of the amount ofalkali required for the condensation. After completion of the reaction,which can be followed by, for example, thin layer chromatography or gaschromatography, the compound of the formula IIb and the amount of alkalirequired for the latter are added. Advantageous reaction temperaturesare from 30° to 50° C. whilst the total reaction time is as a rule from6 to 12 hours.

Particularly suitable alkalis are alkali metal alcoholates, eg. sodiummethylate, ethylate and butylate and potassium methylate, ethylate andbutylate.

Details of the process according to the invention may be found in theExamples, where parts and percentages are by weight, unless statedotherwise.

Using the process according to the invention, it is possible to preparecompounds, and mixtures of compounds, of the general formula I, which donot contain any p,p'-isomers. The compounds and mixtures of compoundsprepared according to the invention may be used as optical brightenersand exhibit particularly good fixing characteristics and a highbrightening yield.

Mixtures of dicyano compounds, especially ofo,m'-dicyano-bis-styrylbenzene and o,p'-dicyano-bis-styrylbenzene witho,o'-dicyano-bis-styrylbenzene, as well as mixtures of the o,m'-compoundand o,p'-compound, are prepared. For instance, preferred mixtures aredescribed in Examples 6, 24 and 25.

EXAMPLE 1

200 parts of 30% strength sodium methylate solution in methanol areadded dropwise in the course of 4 hours to a mixture of 146 parts of 93%strength terephthalaldehyde, 275 parts of 93% strength diethylo-cyanobenzylphosphonate and 1,200 parts of methylglycol acetate at30°-35° C., with vigorous stirring. Stirring is continued for 4 hours at30°-35° C. and 300 parts of 85% strength diethylp-cyanobenzylphosphonate are then added. Thereafter, 306 parts of 30%strength sodium methylate solution are added dropwise in the course of 4hours at 45°-50° C. Stirring is continued for 5 hours at the sametemperature, the mixture is cooled to room temperature and the productis filtered off and washed thoroughly with methanol.

Yield: 260 parts of greenish yellow crystals (melting point 190°-192°C.) of the formula ##STR10##

EXAMPLE 2

The procedure described in Example 1 was followed, but instead of 1,200parts of methylglycol acetate, 1,400 parts of tetrahydrofuran wereemployed.

Yield of product (consisting of a single substance): 73%.

EXAMPLE 3

The procedure described in Example 1 was followed, but instead of 1,200parts of methylglycol acetate, 1,100 parts of ethyl acetate were used.

Yield: as in Example 1.

EXAMPLE 4

The procedure followed was as in Example 1, but dioxane was used as thesolvent.

Yield: 72%.

EXAMPLE 5

The procedure followed was as in Example 1, but isobutyl acetate wasused as the solvent.

Yield: 78%.

EXAMPLE 6

2.34 parts of a 30% strength sodium methylate solution in methanol wereadded dropwise, in the course of 5 hours, to a mixture, stirred at 120rpm, of 10 parts of methylglycol acetate, 1.4 parts ofterephthalaldehyde and 3.3 parts of diethyl o-cyanobenzylphosphonate at28°-32° C. After stirring for a further 4 hours at 40°-45° C., 1.9 partsof diethyl p-cyanobenzylphosphonate were added, and 1.7 parts of a 30%strength solution of sodium methylate in methanol were then introduceddropwise in the course of 6 hours at 35°-40° C. After stirring for afurther 6 hours at 45°-50° C., the greenish white precipitate wasfiltered off.

Yield: 2.55 parts.

According to analysis by gas chromatography, the product is a mixture of##STR11##

This mixture shows especially advantageous properties when used as abrightener for polyesters; in particular, its fixing capacity isexceptionally good for bis-styryl derivatives, and the brightening yieldis high.

EXAMPLES 7-22

The procedure followed was similar to Example 1, except that thefollowing solvents and phosphonates were used:

        Phosphonate ester Phosphonate ester  Example Solvent II a II b     Product      7 Dioxane     ##STR12##      ##STR13##      ##STR14##      8 Ethylacetate     ##STR15##      "      ##STR16##      9 Ethylacetate     ##STR17##      ##STR18##      ##STR19##      10 Butylacetate     ##STR20##      ##STR21##      ##STR22##      11 Butylacetate "     ##STR23##      ##STR24##      12 Methylglycolacetate "     ##STR25##      ##STR26##      13 Methylglycolacetate "     ##STR27##      ##STR28##      14 Methylglycolacetate "     ##STR29##      ##STR30##      15 Methylglycolacetate "     ##STR31##      ##STR32##       16 Ethylglycolacetate     ##STR33##      ##STR34##      ##STR35##      17 Ethylglycolacetate "     ##STR36##      ##STR37##      18 Ethylglycolacetate "     ##STR38##      ##STR39##      19 Ethylglycolacetate "     ##STR40##      ##STR41##      20 Ethylglycolacetate "     ##STR42##      ##STR43##      21 Tetrahydro-furan     ##STR44##      ##STR45##      ##STR46##      22  Tetrahydro-furan "     ##STR47##      ##STR48##      23 Ethylglycolacetate     ##STR49##      ##STR50##      ##STR51##

EXAMPLE 24

20.3 parts of a 30% strength sodium methylate solution in methanol areadded dropwise, in the course of 5 hours, to a mixture, stirred at 120rpm, of 100 parts of methylglycol acetate, 14.4 parts ofterephthalaldehyde and 28.6 parts of diethyl o-cyanobenzylphosphonate at28°-32° C. The mixture is then stirred for 4 hours at 40°-45° C., 15.2parts of diethyl m-cyanobenzyl phosphonate followed by 10.8 parts of 30%strength sodium methylate solution in methanol are then added, and thebatch is stirred for 1 hour at 35° C. 6.8 parts of diethylp-cyanobenzylphosphonate and a further 5 parts of 30% strength sodiummethylate solution are then added, followed by stirring for 5 hours at35°-40° C.

On working up the mixture as described in Example 6, a greenish whitecrystalline product is obtained, which according to analysis by gaschromatography contains ##STR52## This mixture is an excellentbrightener for polyester fabrics and in particular shows good fixingproperties, a reddish tint and a good brightening yield.

EXAMPLE 25

The procedure described in Example 24 is followed, 14.4 parts ofterephthalaldehyde being reacted successively with 25 parts of diethylo-cyanobenzylphosphonate, 15.2 parts of diethyl m-cyanobenzylphosphonateand 10 parts of diethyl p-cyanobenzylphosphonate. A brightener mixturecontaining ##STR53## is obtained; this mixture is also an excellentbrightener for polyesters. I claim: 1. A mixture of optical brightenercompounds consisting of a compound of formula (A) ##STR54## and at leastone compound of formula (B) or (C) where formula (B) is ##STR55## andformula (C) is ##STR56## 2. A mixture according to claim 1 of 65% of acompound of formula (A) and 35% of a compound of formula (C). 3. Amixture according to claim 1 of 60% of a compound of formula (B), 27% ofa compound of formula (A) and 13% of a compound of formula (C). 4. Amixture according to claim 1 of 60% of a compound according to formula(B) and 40% of a compound according to formula (A).

I claim:
 1. A mixture of optical brightener compounds consisting of acompound of formula (A)and at least one compound of formula (B) or (C)where formula (B) is ##STR57## and formula (C) is ##STR58##
 2. A mixtureaccording to claim 1 of 65% of a compound of formula (A) and 35% of acompound of formula (C).
 3. A mixture according to claim 1 of 60% of acompound of formula (B), 27% of a compound of formula (A) and 13% of acompound of formula (C).
 4. A mixture according to claim 1 of 60% of acompound according to formula (B) and 40% of a compound according toformula (A).